It is common practice to detect the moisture level of clothes tumbling in a dryer by the use of sensors located in the dryer drum. The sensors form part of a moisture sensing circuit that develops a voltage signal from the sensors. The voltage signal from the moisture sensing circuit is typically supplied as an input to a microprocessor controller. The microprocessor controller may periodically sample the voltage signal and use the samples to determine when the clothes are dry, near dry, or at a predetermined target level of moisture content, and the drying cycle should terminate.
As can be appreciated, the voltage signal from the sensors and moisture sensing circuit may be highly variable over time and may not accurately reflect the moisture content of the clothing articles. This signal may be effected by noise including noise related to the line current frequency used to operate the clothes dryer. Accordingly, there is a need for a moisture sensing circuit that is able to compensate for noise, and, in particular, noise related to the line operating frequency of the dryer.